The grass is a little greener on the south side of Harkness co-op, where Oberlin's first vegetated green roof has been installed.
The project is part of the College's ongoing initiative to green-up campus, and Harkness Hall fit the bill for a green roof, says Nathan Engstrom, coordinator for the Office of Environmental Sustainability.
Harkness was chosen for its accessible rooftop patio, a 400-square-foot area where students regularly converge. The old roof, which was covered in stone pavers, was also leaking and scheduled for replacement. Keeping the patio space usable was a priority, Engstrom says, and the green roof concept was more cost effective than replacing the pavers.
All of the planning took place last summer, and officials put the project was put on a fast track to get the work done and the specimens planted before winter.
By definition, a green roof is covered with substantial vegetation. The Harkness roof is designed in modules with five varieties of sedum plants. Besides its aesthetic appeal, the main benefits are storm water retention, energy savings, sound insulation, and urban cooling. And because vegetation provides protection from ultraviolet radiation and extreme temperature changes, it increases the life expectancy of the roof, says Amy Mead, business development manager for Weston Solutions, the consulting firm that worked on Harkness.
“The biggest advantage of a green roof is the fact that it will retain an enormous amount of storm water,” Mead says. “We see up to 90 percent storm water retention.”
Potential costs savings have not been estimated for the Harkness project, however, general case studies show a 25 to 50 percent reduction in heating and cooling costs for the floor directly below a green roof, according to Weston Solutions. Although the energy savings pan out across the year, the effects are more noticeable in the summer cooling season.
Engstrom says the green roof also serves an educational purpose on campus.
“This project is a starting point to demonstrate the technology of a green roof and to bring awareness of how it functions,” Engstrom says. The current green roof structure is complete, but features such as monitoring tools for storm water and temperature levels could be added in the future, he says.
“This a very new thing, and everyone can take advantage of its educational role by seeing what a green roof can do for storm water management and insulation.”
Engstrom says no other campus buildings are currently targeted for a green roof replacement, but every project is intended to be more environmentally sustainable than conventional alternatives.